|History of studies at Kotel'nich|
Geological work on the Kotel'nich red beds began rather late, with the ﬁrst geological mapping only 100 years ago (Krotov, 1912). This was because the area was remote from major cities, and seemingly devoid of mineral potential. The Vyatka River had long been a major transport artery, but the town of Kotel'nich remained a very remote outpost of the Russian Empire until the railway from St Petersburg to Vyatka opened in 1905. Following continued repression during Soviet times, and substantial decline of industry after 1990, Kotel'nich remains a remote and undeveloped town.
The geology of the Permian red beds was revised by Ignat'ev (1962, 1963) and Tikhvinskaya (1946), and reviewed by Nalivkin (1973) and Lozovskiy and Esaulova (1998). In these works, the sedimentary rocks were interpreted as fluviatile and lacustrine. Tverdokhlebov and Shminke (1990) were the first to argue that the yellow sandstones of the Boroviki Member (Coffa, 1999) were aeolian in origin. Then, Goman'kov (1997), Coffa (1999), and Golubev (2000) presented summary accounts of the sedimentology and stratigraphy of the Kotel'nich succession, each based on original and independent fieldwork, and Tverdokhlebov (2009) added further first-hand observations.
The Kotel'nich red beds are renowned for their abundant and exquisite tetrapod fossils, and yet earlier geologists did not pay these much attention (see Ochev, 1995; Ochev and Surkov, 2000 for historical surveys). Krotov (1894, 1912) recorded isolated bones from the west bank of the Vyatka River just south of Kotel'nich, at a locality later termed 'Kotel'nich-1'. In 1933, S. G. Kashtanov, a young hydrogeologist from Kazan' University, discovered two complete pareiasaur skeletons near the village of Vanyushonki, on the river bank 18 km south of Kotel'nich, and he found a further two or three in 1935, 2 km upstream (Kashtanov, 1934). The skeletons were incomplete as they had been partially eroded by the action of the Vyatka River, but Kashtanov excavated some of this material and sent it to the Paleontological Institute (PIN) in Moscow.
Right: Map of the Kotel'nich area showing the relatively straight, south-flowing reach of the Vyatka River to the south of the town. Permian strata are exposed on the elevated escarpment along the western bank of the Vyatka River, with most of the vertebrate localities close to the village Boroviki. Numbers with white markers show the locations of logged sections in Benton et al. (2012).
The Moscow palaeontologists came to Kotel'nich, beginning with expeditions led by A. P. Hartmann-Weinberg in 1935, and they found two incomplete skeletons and two skulls of pareiasaurs near the village of Volki. In 1948, a team from PIN led by B. P. V'yushkov, found four pareiasaur skeletons, three of them damaged by erosion, near Boroviki village. The following year, the same team prospected 12 km of the banks of the Vyatka River, from Port Kotel'nich south to Boroviki, and they discovered a further seven complete and six incomplete skeletons. Two further skeletons were reported in 1950 from Boroviki village by D. M. Vologzhanin, but he could not extract them. In their overview of the Russian Permo-Triassic tetrapods, Efremov and V'yushkov (1955) reported 15 pareiasaur skeletons collected by PIN scientists at Kotel'nich.
Renewed investigations by PIN scientists Yu. M. Gubin, M. F. Ivakhnenko, and N. N. Kalandadze turned up isolated pareiasaur and therapsid specimens in several green sandstone lenses higher in the section, in what is now termed the Sokol'ya Gora Member near Agafonovo, a locality they termed Kotel'nich-2. Further excavations began in the 1990s, thanks to the work of D. L. Sumin from Moscow, who collected many tetrapod skeletons, including dicynodonts, dromasaurs, therocephalians, and gorgonopsians, as well as pareiasaurs. He established a fossil-dealing company called Kamyennii Tsvyetok (='Stone Flower') that sold some of the fossils, but the company was dissolved in 1995. In the three years from 1990 to 1992, Sumin and colleagues collected 40 pareiasaur skeletons on the banks of the Vyatka, near the villages of Boroviki and Mukha.
Since 1992, the work has been led by Al'bert Yu. Khlyupin, in conjunction with teams of locally based geologists, school children, and visitors from overseas. These teams excavated both at Port Kotel'nich, where they found many dicynodont skeletons as well as rarer pareiasaurs, and along the southern portion of the section on the banks of the Vyatka where they excavated many pareiasaurs and the extraordinary small climbing reptile Suminia. Khlyupin established a museum in Kotel'nich in 1994, and it has since been designated as a regional museum, the Vyatka Palaeontological Museum. Since 1992, the Museum group has excavated and documented over 390 tetrapod skeletons.